Wheat is grown worldwide and is the most widely adapted cereal. Common wheats are used in a variety of food products such as bread, cookies, cakes, crackers, and noodles. In general the hard wheat classes are milled into flour used for breads and the soft wheat classes are milled into flour used for pastries and crackers. Wheat starch is used in the food and paper industries, as laundry starches, and in other products.
The primary threat to commercial wheat production is weed competition, resulting in decreased grain yields and inferior grain quality. Although cultivation can be used to eliminate weeds, soil from tilled fields is highly vulnerable to wind and water erosion. Due to ease of application and effectiveness, herbicide treatment is the preferred method of weed control. Herbicides also permit weed control in reduced tillage or direct seeded cropping systems designed to leave high levels of residue on the soil surface to prevent erosion. The most significant weed competition in wheat comes from highly related grasses, such as wild oat and jointed goatgrass, and it is difficult to devise effective chemical control strategies for problematic weed species related to the cultivated crop since they tend to share herbicide sensitivities. One approach to solving this problem involves the development of herbicide resistant varieties. In this system, herbicide-is applied “in-crop” to control weeds without injuring the herbicide-tolerant crop plants.
The development of herbicide resistance in plants offers significant production and economic advantages; as such the use of herbicides for controlling weeds or plants in crops has become almost a universal practice. However, application of such herbicides can also result in death or reduced growth of the desired crop plant, making the time and method of herbicide application critical or in some cases unfeasible.
Of particular interest to farmers is the use of herbicides with greater potency, broad weed spectrum effectiveness and rapid soil degradation. Plants, plant tissues and seeds with resistance to these compounds would provide an attractive solution by allowing the herbicides to be used to control weed growth, without risk of damage to the crop. One such class of broad spectrum herbicides are those compounds that inhibit the activity of the acetyl-CoA carboxylase (ACCase) enzyme in a plant. Such herbicides are included in the aryloxyphenoxypropionate (FOP) and cyclohexanedione (DIM) chemical families. For example, wheat is susceptible to many ACCase inhibiting herbicides that target monocot species, making the use of these herbicides to control grassy weeds almost impossible.
Due to the importance of wheat as a crop plant on the world stage, there is a need for wheat hybrids that are resistant to the inhibitory effects of ACCase herbicides, thereby allowing for greater crop yield when these herbicides are used to control grassy weeds.